#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
int main()
{
    char ch[1000];
    scanf("%s", ch);
    int i = 0;
    int len = strlen(ch);
    int end = len - 1;
    for (i = end;i >= 0;i--)
    {
        for (int j = 0;j < end;j++)
        {
            if (ch[j] > ch[j + 1])
            {
                char tmp = ch[j];
                ch[j] = ch[j + 1];
                ch[j + 1] = tmp;
            }
        }
    }
    for (i = 0;i < len;i++)
    {
        printf("%c", ch[i]);
    }
    return 0;
}